The present invention relates generally to imaging systems, and more particularly to an image sensor architecture that integrates the functions of imaging and range-finding.
Image sensors convert an optical image into an electronic signal. An optical image is a visual representation of a scene. A scene contains objects that may be illuminated by light that is visible and/or outside the visible portion of the spectrum (i.e., illuminated by electromagnetic radiation). The light may be from passive (or incidental) light or from active light sources. The light from a scene can be detected by a sensor and converted into an electronic image.
Range finders may be used to determine a relative range to an object. The range may be based on the frame of reference of an observer or may be based upon an arbitrary reference point. A range finder determines ranges to illuminated objects by analyzing the propagation times of propagated signals. Ranging often includes xe2x80x9cbouncingxe2x80x9d (i.e., causing to be reflected) a propagated signal off of an object for which a range is desired and measuring the length of the time required for the signal to propagate. The range can be determined by multiplying the rate of propagation by the time required to propagate the signal from the object to the sensor.
The present invention is directed towards an apparatus and method that integrates the functions of imaging and range-finding. An image sensor is disclosed that contains pixel cells that can individually provide a real-time output signal that is proportional to the instantaneous magnitude of incident electromagnetic radiation upon each pixel cell. The pixel cells of the image sensor can be used to collectively provide an accumulated real-time output signal that is proportional to the instantaneous magnitude of incident electromagnetic radiation upon a plurality of selected pixel cells.
According to one aspect of the invention, a system for range-finding and imaging comprises a pixel array, a pixel selector, and a summer. The pixel array is comprised of pixel cells. Each pixel cell is capable of producing a real-time output signal that is proportional to the instantaneous magnitude of incident radiation upon each pixel cell. The pixel selector is configured to select pixel cells in response to a set of target pixel cells. The summer is configured to accumulate the real-time output signals from a plurality of selected pixel cells and provides an accumulated signal in response.
According to another aspect of the invention, a method for imaging and range-finding comprises selecting a set of pixel cells from within a pixel cell array. A real-time output signal is produced for each selected pixel cell. The real-time output signal is proportional to the instantaneous magnitude of incident radiation upon each selected pixel cell. The real-time output signals from the selected pixel cells are summed. An accumulated signal is provided in response to the sum of the real-time output signals from the selected pixel cells.